环境科学与生态学最新文献

Neotropical regions are responsible for harboring most of the global diversity of freshwater fish, providing essential ecosystem services for society. Human activities (e.g., land use changes) jeopardize aquatic ecosystems as well as species, communities, etc., impairing ecosystem services. We investigate the impact of human disturbance on the foraging ecology of Neotropical freshwater fishes across five Brazilian biomes by stable isotope analysis. We analyzed carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic compositions of Neotropical fishes, sourced from the SIA-BRA dataset. Fishes were categorized into herbivores, omnivores, and carnivores. We tested the correlation between human disturbances, indicated by the human disturbance index (hdi), and changes in fish diets. We expected that the assimilation of C₄‑carbon from exotic forage would increase with higher disturbance levels, while δ¹⁵N levels would similarly rise due to nitrogen input from anthropogenic sources. We found increases in fish δ¹³C with human disturbance increases, suggesting greater assimilation of C₄ carbon in places where native vegetation was replaced by C₄ sources, confirmed by isotopic mixing models. In contrast, δ¹⁵N values did not show a significant relationship with human disturbance, probably due to the complex interactions and multiple sources of nitrogen in disturbed environments. Our finds suggest that stable isotope analysis provides a powerful tool for monitoring the effects of landscape changes on aquatic food webs. Particularly, the δ¹³C values of detritivorous fish that feed on C₄ plant detritus could serve as bioindicators of environmental degradation. However, a specific isotopic characterization of each site would be valuable for more accurate niche information.

The symbiotic relationship between plant roots and soil infiltration is of great significance for sustainable development of the agriculture and forestry. Through detailed summary of the relationship between root morphological parameters and soil infiltration rates in arid and semi-arid grasslands mainly with leguminous herbs, gramineous herbs and shrubs, the mechanisms that key parameters (root length density, surface area density, diameter, biomass density, architecture, secretion and decay rate) disturb soil infiltration through affecting soil structure such as porosity, soil bulk density and soil organic matter (SOM) are elucidated. Furthermore, the degree of root disturbance on soil structure and infiltration rates are partially clarified by constructing quantitatively structural equation modeling path diagrams. The results show roots have the most significant effect to increase soil infiltration rates through increasing non-capillary pores, contributing to >50 % of the positive effect. In contrast, the increased SOM influenced by roots can obstruct soil infiltration and offset about 25 % of the positive effects. In addition, the impact of root disturbance on transport of nutrients, pesticide and pathogenic microorganisms in rhizosphere soil is also discussed to analyze the potential influence on food and water environmental safety. The presence of roots reduces the amount of leachate-prone nutrients, but their disturbance increases the rate of soil infiltration thus accelerates transport of solutes into deeper soil. Meanwhile, the rhizosphere alters the environmental behavior of pesticides and pathogenic microorganisms, increasing risk of plant roots exposure to them. At present, systematically quantifying the interference of plant roots on soil structure and soil infiltration capacity remains a major challenge. It is necessary to further improve the research methodology and strengthen the study of root soil interaction mechanisms, providing scientific basis and technical support for sustainable agricultural development and ecological environment protection.

Climate and landscape structure are widely recognized as the primary drivers of soil erosion; however, the spatiotemporal variability of their effects remains insufficiently understood, limiting our comprehension of the dynamic processes of soil erosion. To address this gap, this study analyzed soil erosion trends on the Loess Plateau from 2000 to 2018. extreme Gradient Boosting was used to identify key climatic and landscape structural factors, while a geographically and temporally weighted regression model was applied to assess the spatiotemporal variability of these influences. The results indicate a decreasing trend in soil erosion from 2000 to 2008, followed by a sharp increase from 2008 to 2018. Grassland edge density emerged as the most important factor, followed closely by grassland percentage and annual precipitation. Temporally, the positive effect of annual precipitation has been intensifying since 2010, contributing to increased erosion, while landscape structural factors progressively enhanced their hydrological regulatory roles, reflecting dynamic interactions with climate. Spatially, the direction of climatic influences remained generally stable, consistently promoting erosion, although by 2018, the effects of average annual temperature and annual sunshine duration reversed to suppress erosion in specific areas. In contrast, landscape structural influences exhibited greater spatial variability, often fluctuating or reversing depending on topography, human activity, and land use. This variability applied specifically and differentially to each metric of fragmentation and diversity, highlighting the critical importance of trade-offs in landscape management. The findings emphasize the complexity and dynamics of soil erosion in response to climate and landscape structure, suggesting implications for the development of spatially targeted soil erosion control strategies that accommodate the phases of temporal variation.

Compared to the general hospital, the children's hospital has significantly higher noise levels. This seriously influences hospital environment quality and medical service level. The noise characteristic and its influence were studied with field measurements and questionnaire surveys conducted in Kunming Children's Hospital. A-weighted equivalent continuous sound level (L_Aeq), percentile sound pressure levels, loudness and sharpness in waiting areas of cardiology, internal medicine, stomatology, intravenous blood collection and VIP departments were acquired and analyzed. Results showed that L_Aeq variation was consistent with the medical service schedule. The children's cries and the broadcast system were regarded as the main noise sources and their suddenness characteristic for a single event were analyzed. Questionnaire survey results revealed that more staff than patients in the waiting areas considered the sound environmental noisy. The ordered logit model analysis showed the subjective noisy evaluation of staff was significantly associated with ten percentile sound level (L₁₀) and five percentile loudness (N₅).

The study of the competitive and selective immobilization properties and mechanisms of pollutants immobilized by metastable biogenic monohydrocalcite is of great importance for the assessment of the eco-environmental effects and applications of hydrated calcite at the Earth's poles. Microbial culture technology was used to induce the synthesis of biogenic monohydrocalcite (BMHC), and mineral characterization, batch adsorption experiments and chemical analyses were further used to investigate the sequestration characteristics, action mechanism, and environmental effects of BMHC on Pb(II)-Ni(II)-Zn(II)-methylene blue (MB) compound pollution. The results show that BMHC is an organic-inorganic mineral composite (about 3.60 % organic matter, Mg/Ca ≈ 0.07). The adsorption and immobilization processes of Pb(II), Ni(II), Zn(II), and MB(I) by BMHC are all better fitted by the pseudo-second-order kinetic equation. The passivation ability of BMHC for contaminants is ranked as Pb(II) ≫ Zn(II) > Ni(II) > MB(I). BMHC exhibits an excellent selective sequestration capacity of Pb(II) (k ≥ 31.89), which is related to the solubility product of the carbonate minerals, the initial concentration of Pb(II), ion exchange and mineral phase transformation. Based on these results, it is proposed that the synthesis and transformation of monohydrocalcite under global warming at the Earth's poles may influence the biogeochemical cycling of environmental pollutants. The study provides a theoretical basis for the environmental effects and geochemical action of biogenic monohydrocalcite and its applications.

In fractured rock aquifers contaminated with trichloroethene (TCE), the extent of groundwater plumes is impacted by degradation occurring within the rock matrix. The objective of this study was to evaluate TCE degradation in rock samples from three sites where in situ conditions may favor natural or enhanced attenuation. Intact rock core microcosms (94 total) were used to assess in situ conditions and enhancement by addition of lactate or lactate + sulfate. A key advance for this study was inclusion of carbon-14 (¹⁴C) labeled TCE in the experimental design, which enables monitoring of ¹⁴C-labeled products in addition to more readily detectable compounds associated with TCE degradation (i.e., cis-1,2-dichloroethene (cDCE), vinyl chloride, acetylene, ethene, and ethane). ¹⁴C-labeled products comprised 35-95 % of the total degradation products recovered over 9-21 months of monitoring, indicating that inclusion of ¹⁴C-TCE was essential to capturing the full potential for abiotic and biotic degradation of TCE. Microcosms infused with TCE but not ¹⁴C-TCE exhibited enrichment in δ¹³C-TCE, and enrichment in δ¹³C-cDCE in microcosms that underwent reductive dechlorination of TCE to cDCE. The results demonstrate the advantages of using diffusion-transport microcosms and ¹⁴C-TCE to document degradation of chlorinated ethenes in fractured rock aquifers.